The present invention relates to a membrane for regenerating a bone, in particular a distraction membrane, suitable for callus distraction, notably in the jaw region, to the use of the membrane for callus distraction, and to methods for callus distraction.
Bone losses are currently generally filled with bone substitute material or with autogenous or allogenic bone.
From a biological view, an autologous spongiosa transplant is the best substitute material for bone. However, such transplants are only available to a limited extent and exhibit a high resorption rate after transplantation.
The materials and techniques employed in the prior art frequently provide inadequate bone quality, so that implants, for example, are not rigidly anchored in the beds. Additionally, the bone substitute is frequently not sufficiently vascularized, and as a result the risk of infection is increased. Methods according to the prior art often also employ growth factors, which significantly increase the costs of the procedures.
Instead of using a bone substitute, lacking bone substance can also be partially filled in by way of bone regeneration. Segmental osseous discontinuity on long bones can thus be treated by way of distraction osteogenesis.
Callus distraction has been known for more than one hundred years. The most important biological stimulus for osteogenesis is mechanical stress. Piezoelectrical forces are released in the process, which activate osteoblasts and osteoclasts. Distraction osteogenesis induces new bone formation by triggering biological growth stimuli by slowly separating bone segments. This method achieves the direct formation of woven bone by way of distraction. Defined tensile stress during bone generation is essential. If such defined tensile stress is applied to bone fragments, the mesenchymal tissues in the gap and on the adjoining fragment ends show osteogenetic capacity. If sufficient vascular potency exists, progressive distraction results in metaplasia of the organized hematoma, also referred to as a blood clot, in a zone of longitudinally arranged, fibrous tissue, which under optimal external and internal conditions can convert directly into woven bone. However, an aggravating factor is that the bone tissue is subject to highly complex control during regeneration.
WO 01/91663 A1 and U.S. Pat. No. 5,980,252 describe devices and methods for callus distraction by way of artificial interfaces, for example membranes. The membranes used there are flat plates or flat small plates, which are usually made of metal, for example titanium. When these plates or small plates are moved for distraction of the bone, the edges and the lateral faces thereof, which form the height of the membrane, graze the neighboring tissue. This results in irritation and further injury of the neighboring tissue, whereby healing may be worsened.
In addition, these flat plates can only be used to distract smaller regions of a bone section that is not planar, which is to say flat, for example of a jaw, because otherwise the membrane is not evenly seated against the bone.